A network-accessible service can update a program provided by a user device by periodically sending code to the user device. The code may represent a current version of the program. Or the code may represent a patch that the user device can use to update the program in piecemeal fashion. In either case, the code can take the form of executable content.
The above approach may have various shortcomings. For instance, it may require a significant amount of time and/or bandwidth to update the user device using executable content. To address this issue, an administrator of the network-accessible service may decrease the frequency at which updates are sent to the user device. This solution, however, is not optimal. Viruses and other types of malicious threats may rapidly evolve. Reducing the frequency at which the user device is kept abreast of code changes may fail to counter new threats in a timely manner, thus exposing the user device to such types of threats.